Question 21 (1 point) In 1965, about 44% of the U.S. adult population had never smoked cigarettes. A national health survey of 1205 US. adults (presumably selected randomly) during 2006 revealed that 615 had never smoked cigarettes. A 96% confidence interval for the proportion of U.S. adults in 2006 that had never smoked is O 0.510 : 0.0004 0 0.510 i 0.014 O 0.510 1 0.030 O 0.510 : 0.028